This is an application for funds to upgrade and refurbish major components of an existing nuclear magnetic resonance animal imaging spectrometer. The deivce is a General Electric CSI-II system that is based on a 31 cm bore 2.0T magnet. It has been in constant intensive use at Yale University School of Medicine since November 1984, and was the third such system delivered by the manufacturer. Advances in the technology and methods of in vivo NMR imaging and spectroscopy have occurred since then that cannot accommodated on this system it uses a Nicolet computer that is no longer supported by the manufacturer, does not possess state of the art digital hardware or software, and its performance for imaging and localised spectroscopy is severely limited by the gradient system. However, it does have a magnet, RF spectrometer, and many other components that are all in excellent order, and has been well maintained by the existing user group. Since 1988 two major upgrades have been available for this system, and these are requested via application. The system is situated in the NMR Laboratory in the Department of Radiology which is component of the NMR Centre at Yale School of Medicine. The primary users will be from Diagnostic Radiology (to study proton relaxation mechanisms in tissues; for studies of diffusion in tissues; to evaluate effects of magnetic susceptibility variations in imaging, including susceptibility contrast materials; to devel fast echo planar and spin tagging techniques for studying myocardial wall motion; and to develop and evaluate F19 imaging as a tool for measuring tissue pO2); from Therapeutic Radiology (to develop NMR imaging as method of determining radiation dose distributions in irradiated gels); from Pediatrics and Neurology (to use p3l and H1 spectroscopy to evaluate the consequences of cerebral hypoxia in neonates); from Cardiology evaluate the effects of systemic acid-base disorders on myocardial energetics and pH regulation using NMR spectroscopy); from Molecular Biophysics and Biochemistry and Surgery (to study the regional metabolism and energy state of tissue skin grafts); and from Albert Einstein College of Medicine (to evaluate the changes in muscle in a rat model of sickle cell vaso-occlusion). The spectrometer would be devoted for 90% of its time to these projects. The NMR Research Group within Radiology comprises 4 Ph.D faculty physicists, 3 postdoctoral fellows, 2 electronic engineers, 2 research technologists and a part-time computer scientist, who would serve as the group to maintain and oversee the operation of the system. A committee of recognised experts in NMR and its application, drawn from within the Medical School and other parts of the University would act as an administrative advisory group. The overall aim of this application is to provide for the continuing demand for advanced NMR techniques in a wide variety of biomedical research for the next 5 to 10 years.